Circuit breaker



Oct. 8, 1957 L. w. DYER ETAL CIRCUIT BREA ER Filed April 12, 1955 Fig.2.

Fig.l.

47 OFF ON 47 OFF Fig.3.

United States Patent CIRCUIT BREAKER Lloyd W. Dyer and Francis L.Gelzheiser, Beaver, la assignors to Westinghouse Electric Corporation,Last Pittsburgh, Pa., a corporation of Pennsylvania Application April12, 1955, Serial No. 500,766

9 Claims. (Cl. 200-116) This invention relates to circuit breakers andmore particularly to circuit breakers for controlling lighting andmoderate power circuits.

An object of the invention is to provide a circuit breaker which is ofsimple and rugged construction, safe and reliable in operation and whichis inexpensive to manufacture.

Another object of the invention is to provide a circuit breakerembodying a thermally responsive element which constitutes both contactcarrying means and the trip means is supported on an actuator in amanner to be trip-free of the actuator upon operation of the trip means.

Another object of the invention is to provide a circuit breakeraccording to the preceding paragraph, in which the contact carryingmeans and the actuator means move in opposite directions upon operationof the trip means to effect opening movement of the contact carryingmeans.

The invention both as to structure and operation, together withadditional objects and advantages thereof, will be best understood fromthe following detailed description thereof when read in conjunction withthe ac companying drawings.

in said drawings:

Figure 1 is a side elevational view with the cover plate partiallybroken away of a circuit breaker embodying the principles of theinvention, the breaker being shown in the closed position.

Fig. 2 is a view similar to Fig. 1 but showing the circuit breaker inthe manually open position.

Fig. 3 is a view similar to Fig. 1 but showing the circuit breaker inthe tripped open position.

Fig. 4 is a vertical structural view taken on line IVIV of Fig. 1 andlooking in the direction indicated by the arrows.

Fig. 5 is an enlarged sectional view of a portion of the mechanism shownin Fig. 4.

Referring to Fig. l of the drawing, the circuit breaker comprisesgenerally an open sided casing or housing 11 and a cover plate 13 ofinsulating material, the cover 13 being shown broken away in Fig. 1 forclearness. Mounted for sliding movement in the housing is a U- shapedactuator or carrier 15 of insulating material. Disposed between the twolegs of the carrier 15 for sliding movement relative thereto is aU-shaped bimetallic switch member 17 having spaced movable contacts 19and 21 thereon for cooperating with spaced stationary contacts 23 and 25respectively. The stationary contact 23 is mounted on the inner end of aconducting strip 27 which, at its outer end, has a terminal connector 29thereon. The stationary contact 25 is mounted on a conducting member 31which is integral with a plug-in type connector 33.

The actuator or carrier 15 and the bimetallic movable switch member 17are biased toward each other by springs 35 tensioned between oppositeend pieces 34 of the switch member 17 and the ends of projections 36 onICC? the actuator 15. The switch member 17 and the actuator 15 arenormally prevented from moving toward each other by the engagement oflatch portion 37 on the lower edges of the U-shaped movable switchmember 17 (Figs. 4 and 5) with spaced latch members 38 disposed in thelower end of the U-shaped actuator 15. A coil spring 39 compressedbetween the bottom of the yoke portion 40 of the actuator 15 and thebottom wall of the housing 11 biases both the actuator 15 and, throughthe latch mechanism 3738, the switch member 17 to the closed contactposition.

An insulating manual operating lever 41 is provided for manually openingand closing the breaker contacts. The operating lever 41 is pivotallymounted on a cylindrical projection 43 of the housing and has a fingerpiece 45 which extends out through an opening 47 in the housing 11. Theoperating lever 41 normally does not engage the actuator 15 but has acam portion 49 integral therewith which is adapted to engage the roundedupper ends 51 of the side members of the actuator 15 upon operation ofthe lever 41 to operate the actuator 15 and the switch member 17 to openthe contacts and permit the spring 39 to close the contacts. The openinglever 41 is normally biased by an overcenter spring 53 to the positionshown in Fig. l.

The circuit breaker is manually operated to the open position bymovement of the operating lever 41 clockwise from the on position(Fig. 1) to the off position (Fig. 2). During this movement of theoperating lever 41, the cam portion 49 engages the upper ends 51 of theactuator 15 and moves the actuator, together with the switch member andmovable contacts 1921 downwardly to the open contact position (Fig. 2)in which a notch 55 in the operating lever engages the ends 51 of theU-shaped actuator 15 and holds the actuator in the open position. Also,during the opening movement of the operating lever 41, the overcenterspring 53 moves overcenter and biases the operating lever 41 to the ofiposition as shown in Fig. 3.

The contacts are closed by reverse movement of the operating lever 41from the ofl position back to the on position causing the operatinglever to release the actuator 15, whereupon the spring 39, which wasfurther compressed during the opening operation, moves the actuator 1.5and the movable contact structure to the closed contact position with asnap action.

The circuit breaker is tripped open automatically in response to lowpersistent overload current by the action of the U-shaped bimetallicswitch member 17. When such a low overload current occurs, the two legsof the bimetallic switch member 17 become heated by the current flowtherethrough and, when heated a predetermined amount, the lower ends ofthe bimetallic legs bend inwardly toward each other and disengage thelatch portions 37 from the latch members 38. The springs 35 thereuponsnap the movable contact structure downwardly to open the contacts, thedownward movement of the movable contact structure relative to theactuator 15 being limited by engagement of the lower edges of thebimetal switch element 17 with the outwardly extending arms orprojections 36 of the actuator 15 as shown in Fig. 3. Upon separation ofthe contacts, the spring 39 moves the actuator 15, together with themovable contact structure, upwardly until it is stopped by engagement ofshoulders 57 on the actuator with the housing 11 as shown in Fig. 3. Theupward movement of the actuator 15 causes the upper ends 51 of the legsthereof to engage a projection 59 on the operating lever 41 and move thelever, together with the finger piece 45, to an indicating position(Fig. 3).

Before the contacts can be closed following a tripping operation, themechanism must be reset and relatched. This is accomplished. by m ng theop r lever 41 clockwise as far as it will go. During this movement ofthe operating lever, the cam surface 49 engages the rounded upper ends51 of the, actuator 15 and forces the actuator downwardly. During thedownward movement of the actuator, the end pieces 34 engage and arestopped by shoulders 61 on the housing 11, and continued movement of theoperating lever thereafter to a position slightl y beyond the offposition moves the actuator downwardly an additional distance to permitthe latch portions 37 (Fig. 5) of the bimetal element to reengage thelatch members 38. The contacts are then closed in the previouslydescribed manner by movement of the operating lever 41 back to the onposition.

Adjusting means is provided to vary the tripping time of the circuitbreaker. The adjusting means comprises a screw 63 (Fig. 5) threadedlyengaging the yoke 40 of the actuator 15. The beveled inner end of thescrew 63 engages inwardly formed portions 65 of the latch members 38.Rotation of the screw 63 moves the latch members 38 relative to thelatch, portions 37 of the bimetallic members 17 thereby varying thetripping point of the breaker. The head of the screw 63 is disposed in acounterbore in the bottom of the yoke 4t) of the actuator 15 and aspring washer 67 is provided to hold the screw in place duringcalibration. Calibration is efiected by inserting a proper tool throughan access opening 69 in the bottom portion of the housing 11. After thecircuit breaker is calibrated, the counterbore is cemented or filledwith a suitable sealing compound round the head of the screw 63 to lockit in its adjusted position. To prevent tampering, a piece of insulatingmaterial 71 is inserted in a slot 73 in the housing thereby closing theaccess opening 69.

Having described the invention in accordance with the patent statutes,it is to be understood that various changes and modifications may bemade therein without departing from the spirit of the invention.

We claim as our invention:

1. A circuit breaker having spaced stationary contacts, a U-shapedcurrent-carrying bimetallic switch member having spaced movable contactsthereon cooperating with said stationary contacts, the high-expansionside of said bimetallic switch member being disposed on the outside ofthe U, a U-shaped actuator supporting said bimetallic switch member,spaced latch members mounted in said actuator normally engaged by sideportions of said bimetallic switch member releasably holding said switchmember and said actuator in predetermined positions relative to eachother, spring means biasing said bimetallic switch members to opencontact position relative to said actuator, other spring means biasingsaid actuator and said bimetallic switch member to closed contactposition, said bimetallic switch member being heated in response tooverload currents and the side portions thereof when heated apredetermined amount bending toward each other to effect release of saidswitch member from said spaced latch members, said spring means beingoperative upon release of said switch member to suddenly move saidswitch member relative to said actuator to open contact position, manualoperating means adjacent one end of said actuator movable to on and offpositions, said operating means when moved to said off position engagingand moving said actuator actuator normally engaged by side portions ofsaid bimetallic switch member releasably holding said switch member andsaid actuator in predetermined positions relative to each other, springmeans biasing said bimetallic switch members to open contact positionrelative to said actuator, other spring means biasing said actuator andsaid bimetallic switch member to closed contact position, a pivotedoperating lever adjacent one end of said actuator movable to an on andan 0113 position and disposed to engage and move said actuator and saidswitch member to open contact position, said operating lever when movedto said off position and released positively holding said actuator andsaid switch member in open contact position, said bimetallic switchmember being heated in response to overload currents and the sideportions thereof when heated at predetermined amount bending toward eachother to effect release of said switch member from said spaced latchmembers, said spring means being operative upon release of said switchmember to suddenly move said switch member relative to said actuator toopen contact position.

3. A circuit breaker having spaced stationary contacts, a U-shapedcurrent-carrying bimetallic switch member having spaced movable contactsthereon cooperating with said stationary contacts, the high-expansionside of said bimetallic switch member being disposed on the outside ofthe U, a U-shaped actuator supporting said bimetallic switch member,spaced latch members mounted in said actuator, normally engaged by sideportions of said bimetallic switch member releasably holding said switchmember and said actuator in predetermined positions relative to eachother, spring means biasing said bimetallic switch members to opencontact position relative to said actuator, other spring means biasingsaid actuator and said bimetallic switch member to closed contactposition, a pivoted operating lever disposed adjacent one end of saidactuator and movable to open and closed positions to effect movement ofsaid actuator and said switch member to. open and closed contactpositions, said bimetallic switch member being heated in response tooverload currents and the side portions thereof when heated apredetermined amount bending toward each other to efiect release of saidswitch member from said spaced latch members, said spring means beingoperative upon release of said switch member to suddenly move saidswitch member relative to said actuator to open contact position, saidother spring means upon release of said switch member moving saidactautor to cause it to engage and move said operating lever to anindicating position.

4. A circuit breaker comprising a housing, spaced stationary contactsmounted in said housing, a U-shaped actuator movable in said housing toopen and closed contact positions, a U-shaped bimetalliccurrent-carrying switch member having spaced movable contacts thereoncooperating with said stationary contacts, said bimetallic switch memberbeing disposed between the sides of said U-shaped actuator for limitedmovement relative thereto, spaced latch members mounted between the sidemembers of said actuator normally engaged by latch portions on the sidemembers ofsaid U-shaped bimetallic switch member releasably holding saidswitch member in closed contact position in the closed contact positionof said actuator, a compression spring biasing said bimetallic switchmember to open contact position relative to said actuator, other springmeans biasing said actuator to closed contact position, thermal bendingof said bimetallic switch member causing the side portions thereof tomove toward each other to effect release of said switch member from saidactuator, and said spring means being operative upon release of saidswitch member to suddenly move said switch member to the open contactposition, and an operating lever for moving said actuator and saidswitch member to open contact position and for engaging and holding saidactuator and said switch member in said open contact position. when saidlever is moved to open said contacts and then released.-

5. A circuit breaker comprising a casing, stationary contact means,movable contact means cooperating with said stationary contact means, anactuator slidable within said casing, a bimetallic latch meansreleasably connecting said movable contact means with said actuator forunitary movement to open and close said contact means, a spring at alltimes biasing said actuator in contact closing direction, spring meansat all times biasing said movable contact means in opening directionrelative to said actuator and operable to move said movable contactmeans to open contact position upon release of said bimetallic latchmeans, an operating lever pivotally mounted adjacent one end of saidactuator movable to on and off positions but normally disengaged fromsaid actuator in the closed contact position of said actuator, saidpivoted operating lever when moved to said off position engaging andmoving said actuator to the open contact position, and said operatinglever when released in said ofi position positively holding saidactuator in open contact position.

6. A circuit breaker comprising a casing, stationary contact means,movable contact means cooperating with said stationary contact means, anactuator slidable within said casing, a bimetallic latch meansreleasably connecting said movable contact means with said actuator orunitary movement to open and close said contact means, a spring at alltimes biasing said actuator in contact closing direction, spring meansat all times biasing said movable contact means in opening directionrelative to said actuator and operable to move said movable contactmeans to open contact position upon release of said bimetallic latchmeans, an operating lever pivotally mounted adjacent one end of saidactuator movable to on and off positions but normally disengaged fromsaid actuator in the closed contact position of said actuator, saidpivoted operating lever when moved to said ofi position engaging andmoving said actuator to the open contact position, and said spring uponrelease of said bimetallic latch means moving said actuator to aposition where it engages and moves said operating lever to anindicating position other than said on and off positions.

7. A circuit breaker comprising stationary contact means, cooperatingmovable contact means, a U-shaped actuator having spaced side membersmovable to open and closed positions, a U-shaped bimetallic switchmember having spaced side portions and mounting said movable contactmeans, said U-shaped switch member being disposed between the spacedside members of said U- shaped actuator for movement relative to saidactuator to open contact position, spaced latch members mounted betweenthe spaced side members of said U-shaped actuator normally engaged bythe spaced side portions of said U-shaped switch member releasablyrestraining said switch member in closed contact position in the closedposition of said actuator, said switch member upon release thereof beingmovable relative to said actuator to open contact position, andadjusting means for simultaneously adjusting the positions of saidspaced latch members relative to the side portions of said switchmember.

8. A circuit breaker comprising a casing, stationary contact means, anactuator slidable in said casing and movable to open and closedpositions, a movable contact structure having movable contacts thereoncooperating with said stationary contact means, bimetallic latch meanson said movable contact structure, latch means on said actuator normallyengaged by said bimetallic latch means releasably holding said movablecontact structure in closed contact position in the closed position ofsaid actuator, a manual operating lever pivotally mounted on said casingadjacent one end of said actuator and movable to on and off positions,biasing means biasing said pivoted operating lever to said on positionswhere it is disengaged from said actuator in the closed position of saidactuator, and a cam surface on said operating lever engaging and movingsaid actuator to open contact position when said operating lever ismoved to the off position.

9. A circuit breaker comprising a casing, stationary contact means, anactuator mounted in said casing and movable to open and closedpositions, a movable contact structure having movable contact meansthereon cooperating with said stationary contact means, said movablecontact structure being movable relative to said actuator to open andclosed contact positions, latch means comprising bimetallic latch meanson said movable contact structure and latch means on said actuatornormally engaged by said bimetallic latch means to releasably maintainsaid movable contact structure in closed contact position in the closedposition of said actuator, said actuator and said movable contactstructure moving in opposite directions upon release of said latch meansto effect opening of said contact means, a manual operating leverpivotally mounted on said casing and movable to on and off positions, aprojection on said operating lever cooperating with said actuator toeffect movement of said actuator to open and closed positions, andanother projection on said operating lever cooperating with saidactuator when said latch means is released to position said operatinglever in an indicating position other than said on and oil positions.

References Cited in the file of this patent UNITED STATES PATENTS

